* [Qemu-devel] [PATCH v5] migration/block: use blk_pwrite_zeroes for each zero cluster
@ 2017-04-12 13:07 jemmy858585
2017-04-12 13:19 ` Eric Blake
0 siblings, 1 reply; 2+ messages in thread
From: jemmy858585 @ 2017-04-12 13:07 UTC (permalink / raw)
To: qemu-devel; +Cc: stefanha, famz, quintela, dgilbert, qemu-block, Lidong Chen
From: Lidong Chen <lidongchen@tencent.com>
BLOCK_SIZE is (1 << 20), qcow2 cluster size is 65536 by default,
this maybe cause the qcow2 file size is bigger after migration.
This patch check each cluster, use blk_pwrite_zeroes for each
zero cluster.
Signed-off-by: Lidong Chen <lidongchen@tencent.com>
---
migration/block.c | 35 +++++++++++++++++++++++++++++++++--
1 file changed, 33 insertions(+), 2 deletions(-)
diff --git a/migration/block.c b/migration/block.c
index 7734ff7..41c7a55 100644
--- a/migration/block.c
+++ b/migration/block.c
@@ -885,6 +885,8 @@ static int block_load(QEMUFile *f, void *opaque, int version_id)
int64_t total_sectors = 0;
int nr_sectors;
int ret;
+ BlockDriverInfo bdi;
+ int cluster_size;
do {
addr = qemu_get_be64(f);
@@ -919,6 +921,15 @@ static int block_load(QEMUFile *f, void *opaque, int version_id)
error_report_err(local_err);
return -EINVAL;
}
+
+ ret = bdrv_get_info(blk_bs(blk), &bdi);
+ if (ret == 0 && bdi.cluster_size > 0 &&
+ bdi.cluster_size <= BLOCK_SIZE &&
+ BLOCK_SIZE % bdi.cluster_size == 0) {
+ cluster_size = bdi.cluster_size;
+ } else {
+ cluster_size = BLOCK_SIZE;
+ }
}
if (total_sectors - addr < BDRV_SECTORS_PER_DIRTY_CHUNK) {
@@ -932,10 +943,30 @@ static int block_load(QEMUFile *f, void *opaque, int version_id)
nr_sectors * BDRV_SECTOR_SIZE,
BDRV_REQ_MAY_UNMAP);
} else {
+ int i;
+ int64_t cur_addr;
+ uint8_t *cur_buf;
+
buf = g_malloc(BLOCK_SIZE);
qemu_get_buffer(f, buf, BLOCK_SIZE);
- ret = blk_pwrite(blk, addr * BDRV_SECTOR_SIZE, buf,
- nr_sectors * BDRV_SECTOR_SIZE, 0);
+ for (i = 0; i < BLOCK_SIZE / cluster_size; i++) {
+ cur_addr = addr * BDRV_SECTOR_SIZE + i * cluster_size;
+ cur_buf = buf + i * cluster_size;
+
+ if ((!block_mig_state.zero_blocks ||
+ cluster_size < BLOCK_SIZE) &&
+ buffer_is_zero(cur_buf, cluster_size)) {
+ ret = blk_pwrite_zeroes(blk, cur_addr,
+ cluster_size,
+ BDRV_REQ_MAY_UNMAP);
+ } else {
+ ret = blk_pwrite(blk, cur_addr, cur_buf,
+ cluster_size, 0);
+ }
+ if (ret < 0) {
+ break;
+ }
+ }
g_free(buf);
}
--
1.8.3.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [Qemu-devel] [PATCH v5] migration/block: use blk_pwrite_zeroes for each zero cluster
2017-04-12 13:07 [Qemu-devel] [PATCH v5] migration/block: use blk_pwrite_zeroes for each zero cluster jemmy858585
@ 2017-04-12 13:19 ` Eric Blake
0 siblings, 0 replies; 2+ messages in thread
From: Eric Blake @ 2017-04-12 13:19 UTC (permalink / raw)
To: jemmy858585, qemu-devel
Cc: famz, qemu-block, quintela, dgilbert, stefanha, Lidong Chen
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On 04/12/2017 08:07 AM, jemmy858585@gmail.com wrote:
> From: Lidong Chen <lidongchen@tencent.com>
>
> BLOCK_SIZE is (1 << 20), qcow2 cluster size is 65536 by default,
> this maybe cause the qcow2 file size is bigger after migration.
s/maybe/may/
s/is bigger/to be bigger/
> This patch check each cluster, use blk_pwrite_zeroes for each
s/check/checks/
s/use/using/
> zero cluster.
>
> Signed-off-by: Lidong Chen <lidongchen@tencent.com>
> ---
Please use this space (after the ---) to state how v5 differs from v4,
in order to save reviewers some time.
> migration/block.c | 35 +++++++++++++++++++++++++++++++++--
> 1 file changed, 33 insertions(+), 2 deletions(-)
>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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2017-04-12 13:07 [Qemu-devel] [PATCH v5] migration/block: use blk_pwrite_zeroes for each zero cluster jemmy858585
2017-04-12 13:19 ` Eric Blake
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